When I listen to music, I want it to sound as close to the original studio performance as poss, so it should be stereo (where it exists) and remastered from the original master tapes, any faults or distortions etc. should be removed electronically.
An example of what should be done and what it should sound like is "The Motown box" set.
Comparing a track from this CD to the box set is like comparing a roller skate to a Rolls Royce, as ALL THE TRACKS ARE BAD QUALITY MONO. Yes there are die hard enthusiasts who insist Motown must be heard in mono, don't they have 2 ears.
There are statements made that the stereo versions were done by inexperiened engineers as an afterthought and were poor mixes, yes indeed this is correct, they were at first done often by inexperienced engineers and defo as an after thought as stereo had not caught on for pop as opposed to classical music, also AM mono radio ruled, however and it's a BIG HOWEVER, many tracks were subsequently remixed by experts who often tried to get a similar sound balance to the original mono balance, THESE TYPE OF STEREO REMASTERS SOUND SO MUCH BETTER THAN THE RATHER DISTORTED NASTY MONO VERSIONS, we do have 2 ears, so hear in stereo by nature, CB
PS Putting it another way, on these mono tracks much of the sound is missing, you just cannot hear certain instruments etc and Diana's voice is screechy and distorted, in a good stereo remix you will hear what she really sounded like, human as opposed to alien.
PPS Try "Gold" or No 1's the USA version or " Anthology" THE 2001 VERSION AS THERE ARE AT LEAST 4 CD'S BY THE SAME TITLE.